The invention relates to a medical instrument having a tubular shaft, comprising a movable grip element and a coupling portion through which the tubular shaft is connected or can be connected to the tubular shaft. The movable grip element is connected or can be connected to a force transmission element axially movable in the direction of the longitudinal axis of the tubular shaft. Motion of the at least one movable grip element translates into axial motion of the force transmission element.
A handle of this type is disclosed for example in the German company brochure of Karl Storz GmbH and CO., Tuttlingen, xe2x80x9cKARL STORZxe2x80x94ENDOSKOPExe2x80x9d, Vol. xe2x80x9cEndoskopische Chirurgiexe2x80x9d, 2nd Edition Jan. 1994, page DGC 5/1A.
Tubular shaft instruments are used in various types of operative procedures on the human and animal body, in particular for minimally invasive surgery. Such instruments can be formed as pinchers, for example preparation and grasping forceps, forceps for separating or cutting tissue as well as for stamping or punching and the like. The instruments are distinguished according to their various functions by the corresponding configuration of the tools at their distal end. Cutting tools, grasping tools or stamping or punching tools can be provided at the distal end of the tubular shaft, where the instrument comprises at least one movable tool, for example in the form of a jaw part. However, two movable tools can be provided at the distal end of such instruments.
Tubular shaft instruments comprise a handle at the proximal end of the shaft for actuating the at least one movable tool. The shaft of the instrument is normally connected to a coupling portion of the handle in non-releasable or releasable manner. In addition, the handle comprises at least one movable grip element for the purpose of actuating the at least one movable tool at the distal end. To actuate the at least one movable tool at the distal end of the tubular shaft, the at least one movable grip element of the handle is connected with the at least one movable tool via a force transmission element axially movable in the direction of the longitudinal axis of the shaft, for example a push or pull rod. Consequently, movement of the movable grip element, for example a pivotal or axial movement, is translated into axial relative motion of the force transmission element with respect to the shaft and finally into motion of the movable tool.
A handle of the mentioned type is known in various configurations. Normally, the handle comprises a second grip element which is either fixed to be immovable or is also movable. Such a handle can also be formed in the manner of a scissors handle, where both grip elements extend to the side from the shaft of the instrument, as is the case in the company brochure mentioned above. In this type of handle the at least one movable grip element is pivotally connected with the other grip element about a pivot axis running transversely to the longitudinal axis of the shaft. In the sense of the present invention, the handle however can also be formed as a type of pistol grip element, so that the handle can be held as a bar grip element in the fist of one hand.
Common to all of these known handles is that the handle in the condition of being connected to the shaft has a fixed angular position with respect to the shaft, i.e. the handle axis and the longitudinal axis of the shaft form a fixed angle to one another. A handle having a fixed angular disposition with respect to the shaft axis is however not always adapted with respect to its handling properties to the needs of the physician operating the instrument. Depending on the habits of different physicians, different grip element positions are desired for the same type of handle. To always have the optimal ergonomic handle available, it would therefore be necessary to provide a set of several handles for each type of handle, which would then allow each different angular position with respect to the shaft. Thus each physician could then select the most ergonomic handle for himself. In case the handle is not exchangeable, this would mean that a complete set of such instruments would need to be provided for each tubular shaft instrument with handles having differing angles.
In certain cases, it can also be desirable or necessary that the handle of the same instrument be able to undertake different positions during an operative procedure, to therefore allow the most comfortable or convenient positioning of the handle for the operative procedure being carried out. With the known handles, which would be present as a complete set, this would mean that the handle would have to be exchanged several times during the operation or if the handles are not removable, even the entire instrument would have to be exchanged, which would prolong the operation time.
The known handles therefore have drawbacks with respect to their ergonomic properties.
From DE 196 32 135 A, a medical instrument is known which comprises a tubular shaft. The shaft can be pushed with its guide member and its screw member via a sliding member and a rotatable tappet. The latter is moved by the pressure of an end-surface of an eccentric disc when it rotates about a point. An eccentric disc is rotatably mounted between an upper baring disc and a lower baring disc with a screw. The handle of this known instrument can be pivoted relative to the tubular shaft. However, the mechanism of the force transmission from the movable grip element to the shaft which is the force transmission element of this known instrument, is disadvantageous because of the enhanced friction between the outer surface of the eccentric disc and the tappet.
An object of the present invention is therefore to provide an improved handle of the mentioned type, such that the handle allows ergonomic work with the tubular shaft instrument, without having to exchange the handle or even the entire instrument, wherein the force transmission mechanism between the movable grip element and the force transmission element is also improved.
This object is achieved by a handle for a medical instrument having a tubular shaft, comprising:
at least one movable grip element for being connected to a force transmission element axially movable in direction of a longitudinal axis of said tubular shaft to transfer motion of said at least one movable grip element into an axial motion of said force transmission element,
a coupling portion for connecting said tubular shaft with said handle,
said coupling portion being pivotal and lockable relative to a handle axis about a pivot axis running transversely to said longitudinal axis of said tubular shaft,
a control element formed as a double-arm lever, a first lever arm of which being connected to said at least one movable grip element, and a second lever arm of which being connected to said force transmission element, such that motion of said movable grip element causes a rotation of said control element, wherein said control element translates said rotation into an axial movement of said force transmission element.
Thus according to the invention, the coupling portion, which couples or can couple the handle to the tubular shaft, is configured to be pivotal and lockable, where it is achieved that the handle can be set at different angular positions with respect to the shaft. The adjusted angular position of the handle can be locked to rigidly interconnect the shaft with the handle, thereafter the tubular shaft instrument can then be employed in an operative procedure. With the pivotal configuration of the coupling portion, the physician can adjust the ergonomic angular position between the handle and the shaft, which is optimal for himself, without having to exchange the handle or the entire instrument. The handle according to the present invention is therefore substantially improved with respect to ergonomics.
When adjusting the handle axis with respect to the longitudinal axis of the shaft, the problem arises that the force transmission element must be so connected to the movable grip element that the motion of the movable grip element at any angular position translates into axial movement of the force transmission element. The force transmission element in the conventional handles, which normally is configured as a push or pull rod, is directly connected to the movable grip element at its proximal end. This type of connection of the force transmission element however cannot be maintained when the handle can be disposed at different angles with respect to the shaft.
This would mean that the force transmission element would also have to be bent or angled in the region of the pivotal axis of the coupling portion, where a compensation for the length of the force transmission element would also have to be provided. The use of a flexible force transmission element would also have to be provided. The use of a flexible force transmission element, which could account for the angled region would be disadvantageous, because greater friction would occur in the region of the angled components.
According to the present invention, a force transmission mechanism is provided between the movable grip element and the force transmission element, by which a control element is disposed between these two parts whose one lever arm is connected with the movable grip element and whose other lever arm is connected to the force transmission element. The movable grip element thus engages with the one lever arm of the control element and the force transmission element engages with the other lever arm of the control element. Actuating the movable grip element causes rotation of the control element, which is translated by the control element via the second lever arm into an axial movement of the force transmission element.
This type of transmission mechanics from the movable grip element to the force transmission element enable force transmission independent of the respectively adjusted pivot position of the coupling portion and thus the respectively adjusted pivot position of the handle. Thus the further advantage is achieved that the force transmission ratio can be selected to be the same in any pivot position of the handle with respect to the shaft. It is then avoided that differing forces are exerted by the physician when actuating the tool at the distal end of the shaft depending on the pivot position of the handle.
In a preferred embodiment, the pivot axis of the coupling portion coincides with a pivot axis of the control element.
A simple construction of the force transmission mechanism is achieved by this feature, because only a single pivotal mounting need be provided for the coupling portion and for the control element.
In a further preferred embodiment, the control element is connected to the coupling portion and rotates with the same when pivoting the coupling portion to set the angular position of the handle, where the connection to the movable grip element for pivoting the control element is releasable and after pivoting it is re-established.
The feature has the advantage that when the coupling portion is pivoted to adjust the handle at a different angle with respect to the longitudinal axis of the shaft, the control element is pivoted at the same time so that the position of the control element is adapted to the newly adjusted angular position of the handle. This avoids any change in the force transmission without having to additionally manipulate the control element.
In a further preferred embodiment, the at least one movable grip element is connected to a first lever arm of a further double-arm lever, whose other lever arm is connected to the second lever arm of the control element, where a pivot axis of the lever coincides with the pivot axis of the coupling portion.
This achieves a kinematically favorable force transmission from the movable grip element to the control element, which allows high force transmission at all angular positions.
Preferably, the second lever arm of the lever is interconnected to the control element via a pin, where several holes are provided in the control element arranged at a circular section thereof, through which, depending on the pivot position of the coupling portion, the pin is engageable with one of the holes.
This feature is of particular advantage, especially with the above-mentioned feature that the control element being pivotable together with the coupling portion, because the mentioned lever can be easily disengaged in any adjusted pivot position of the coupling portion before pivoting the control element and can be re-engaged after pivoting.
In a further preferred embodiment, the coupling portion is lockable by means of a locking mechanism in several pivot positions in an angular range of up to about 240xc2x0 with respect to the longitudinal axis of the tubular shaft.
According to this feature, the handle can be pivoted in an angular range between about xe2x88x92120xc2x0 and about +120xc2x0 and be locked in at least two, preferably however a plurality of pivot positions. The ergonomics of the handle with its angular position with respect to the shaft can be adjusted within a large angular range at the desire of the physician. The pivot range however can also be smaller, for example between about xe2x88x9290xc2x0 and +90xc2x0 or between about 0xc2x0 and +120xc2x0 to name a few examples.
Preferably, the locking mechanism comprises a locking nose engageable with recesses in the coupling portion. The locking mechanism further comprises a button so that the locking nose is disengageable with the respective recess when depressing the button.
This type of locking and disengaging the coupling portion advantageously leads to a simple operation of the pivoting and locking of the handle.
In a further preferred embodiment of the invention, the pin is connected to the button and is disengageable from the respective hole in the control element by depressing the button.
With this feature, both the construction of the handle is simplified and the manipulation operations are improved, because only one button need be actuated to unlock both the coupling portion and the control element for pivoting.
In a further preferred embodiment, the second lever arm of the control element comprises a recess formed as a guide slot in which a pin connected to the force transmission element is axially guided.
With this configuration of the control element and the correspondingly formed guide slot, a translation of the pivotal movement of the control element into an axial movement of the force transmission element is achieved in constructively very simple manner.
Alternatively, the force transmission element can also be connected to the control element via a lever.
In this configuration, the lever is then journaled to one end of the control element, where a pivoting of the control element then rotates the lever and the rotation of the lever then causes translational motion of the force transmission element in the manner of a piston rod.
In a further preferred embodiment, the coupling portion comprises a receptor for a proximal end of the force transmission element, where the receptor is axially movable and connected to the pin or to the lever.
In this configuration, the force transmission element is not connected directly to the control element, but through a receptor lying outside of the control element. The advantage is that the connection between the force transmission element and the control element is particularly simple to produce. In addition, this configuration allows the possibility of connecting the force transmission element releasably with the handle.
Preferably, the receptor comprises a locking mechanism for releasably connecting the force transmission element to the coupling portion.
The advantage is that the force transmission element can be removed from the coupling portion and therefore from the handle, where the force transmission element after removal from the handle can be more easily cleaned.
In a further preferred embodiment, the coupling portion comprises a receptor for the tubular shaft for releasably connecting the shaft with the coupling portion.
The advantage is that the shaft can also be removed from the handle, where the ability to clean such an instrument with a tubular shaft is further improved.
An instrument comprising a tubular shaft, at least one movable tool at the distal end of the shaft and a force transmission element arranged to be axially movable in the tubular shaft for actuating the at least one movable tool, is advantageously equipped with a handle according to the invention having one or more of the above features.
Preferably, the tubular shaft and/or the force transmission element is releasably connected to the handle and/or the force transmission element is releasably connected to the tubular shaft. With the releasable configuration of the shaft and the force transmission element, the instrument can be disassembled into the shaft, the force transmission element and the handle, where each of the assemblies can be better cleaned.
Further advantages result from the following description and the appended drawings. It will be understood that the above-mentioned features and those to be described below are applicable not only in the given combinations, but also in other combinations or when taken alone without departing from the scope of the present invention.
An embodiment of the invention is described below in conjunction with the drawings.